The present invention relates generally to loaders and, more particularly, to an automatic locking pin retraction mechanism for a skid-steer loader to prevent the boom arms from engaging extended locking pins when the boom arms are moving upwardly from beneath the pins.
Locking pins, such as described in U.S. Pat. No. 3,730,362, have been employed on skid-steer loaders to provide a convenient mechanism for locking the boom arms at a predetermined height for a vairety of reasons, including inspection, maintenance and repair of the loader. During normal operation of the loader, the locking pins are retracted out of the generally vertical path of movement of the boom arms. If the operator wishes to lock the boom arms in an elevated position, he would raise the boom structure, extend the locking pins within the path of movement of the boom arms and lower the boom structure until the boom arms are resting upon the locking pins.
When the boom arms are lifted upwardly, particularly when lifting a load, a considerable amount of force is exerted on the boom arms to raise the boom structure. If the locking pins are extended within the path of movement of the boom arms when the boom arms are below the locking pins, engagement between the boom arms and the locking pins can cause substantial damage to either the boom sturcture itself or the locking pin mechamism or, more likely, to both.
Accordingly, it would be desirable to provide a locking pin retraction mechanism that would automatically retract extended locking pins when the boom arms are below the locking pins and moving upwardly toward engagement therewith.